Image predictive encoding and decoding device

ABSTRACT

An image predictive encoding device can efficiently encode an image, while suppressing an increase in prediction information and reducing the prediction error of a target block. In an image predictive encoding device, according to one embodiment, to produce a prediction signal of a partition in a target region, it is decided whether prediction information of a neighbouring region can be used. When prediction information of the neighbouring region can be used, a region width of the partition where the prediction information of the neighbouring region is used to produce the prediction signal is determined. The prediction signal of the target region is produced from a reconstructed signal based on at least one of the region width, the prediction information of the target region, and the prediction information of the neighbouring region. The prediction information, information identifying the region width, and a residual signal are encoded.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/348,504 filed on Nov. 10, 2016, which is a continuation of U.S.application Ser. No. 14/581,705 filed on Dec. 23, 2014, which is acontinuation of U.S. application Ser. No. 13/240,559 filed on Sep. 22,2011, which is a continuation of PCT/JP2010/054441, filed Mar. 16, 2010,which claims the benefit of the filing date under 35 U.S.C. §119(e) ofJP2009-069975, filed Mar. 23, 2009, all of which are incorporated hereinby reference.

TECHNICAL FIELD

The present invention relates to an image predictive encoding/decodingsystem. More particularly, the present invention relates to an imagepredictive encoding device, an image predictive encoding method, animage predictive encoding program, an image predictive decoding device,an image predictive decoding method, and an image predictive decodingprogram that perform predictive encoding and predictive decoding byusing region division.

BACKGROUND ART

Compression encoding technology is used in order to efficiently transmitand store still image data and moving image data. The MPEG-1 to 4 andITU (International Telecommunication Union) H.261 to H.264 systems arewidely used for a compression encoding system for moving pictures.

SUMMARY OF INVENTION

An image prediction encoding/decoding system may produce a productionsignal for each block unit. However, since the location and movement ofa moving object may be arbitrarily set in a video, when the picture isdivided into blocks at equal intervals, there are cases that two or moreregions with different movements and patterns may be included in theblock. In such a case, the prediction encoding of the moving image maycause a large prediction error near the edge of the moving object.

In order to accommodate local feature changes in images and suppress anincrease in prediction error, a plurality of prediction types withdifferent block sizes may be prepared. As the block size becomessmaller, however, additional information to produce the predictionsignal (motion vector etc.) may be needed for each small block,resulting in an increase in code amount of the additional information.In addition, when many block sizes are prepared, mode information toselect the block size may be needed, also resulting in an increase incode amount of the mode information.

One aspect of the present embodiments of the image predictionencoding/decoding system may include an image predictive encodingdevice, an image predictive encoding method, and an image predictiveencoding program that can efficiently encode an image, while suppressingan increase in prediction information, such as additional information(motion vectors etc.) and mode information, and reducing the predictionerror of the target block. Additionally, another aspect of the presentembodiments aims to provide an image predictive decoding device, animage predictive decoding method, and an image predictive decodingprogram that correspond to such encoding aspect.

One aspect of the image prediction encoding/decoding system relates toencoding an image. An image predictive encoding device according to oneembodiment may include: (a) a region division unit for dividing an inputimage into a plurality of regions; (b) a prediction informationestimation unit for producing a prediction signal of a target regionamong the plurality of regions from a reconstructed signal and obtainingprediction information that is used to produce the prediction signal, asprediction information associated with the target region; (c) aprediction information encoding unit for encoding the predictioninformation associated with the target region; (d) a decision unit formaking a comparison of the prediction information associated with thetarget region and prediction information associated with a neighbouringregion located adjacent to the target region and deciding, based on aresult of the comparison, whether the prediction information associatedwith the neighbouring region can be used to produce the predictionsignal of the target region; (e) a region width determination unit for,when it is decided by the decision unit that the prediction informationassociated with the neighbouring region can be used to produce theprediction signal of the target region, determining a region width of apartition that is included in the target region and where the predictioninformation associated with the neighbouring region is used to producethe prediction signal; (f) a region width encoding unit for encodinginformation identifying the region width associated with the targetregion; (g) a prediction signal production unit for producing theprediction signal of the target region from the reconstructed signal byusing at least one of the prediction information associated with thetarget region, the prediction information associated with theneighbouring region, and the region width; (h) a residual signalproduction unit for producing a residual signal between the predictionsignal of the target region and the original signal of the targetregion; (i) a residual signal encoding unit for encoding the residualsignal; (j) a residual signal restoration unit for producing a decodedresidual signal by decoding encoded data of the residual signal; (k) anadding unit for producing a reconstructed signal of the target region byadding the prediction signal to the decoded residual signal; and (1) astorage unit for storing the reconstructed signal of the target region.

In addition, an image predictive encoding method according to oneembodiment includes: (a) a region division step for dividing an inputimage into a plurality of regions; (b) a prediction informationestimation step for producing a prediction signal of a target regionamong the plurality of regions from a reconstructed signal and obtainingprediction information that is used to produce the prediction signal, asprediction information associated with the target region; (c) aprediction information encoding step for encoding the predictioninformation associated with the target region; (d) a decision step formaking a comparison of the prediction information associated with thetarget region and prediction information associated with an neighbouringregion located adjacent to the target region and deciding, based on aresult of the comparison, whether the prediction information associatedwith the neighbouring region can be used to produce the predictionsignal of the target region; (e) a region width determination step for,when it is decided in the decision step that the prediction informationassociated with the neighbouring region can be used to produce theprediction signal of the target region, determining a region width of apartition that is included in the target region and where the predictioninformation associated with the neighbouring region is used to producethe prediction signal; (f) a region width encoding step for encodinginformation identifying the region width; (g) a prediction signalproduction step for producing the prediction signal of the target regionfrom the reconstructed signal by using at least one of the predictioninformation associated with the target region, the predictioninformation associated with the neighbouring region, and the regionwidth; (h) a residual signal production step for producing a residualsignal indicative of a difference between the prediction signal of thetarget region and the original signal of the target region; (i) aresidual signal encoding step for encoding the residual signal; (j) aresidual signal restoration step for producing a decoded residual signalby decoding encoded data of the residual signal; (k) a reproduced signalproduction step for producing a reconstructed signal of the targetregion by adding the prediction signal to the decoded residual signal;and (1) a storage step for storing the reconstructed signal of thetarget region.

Furthermore, an image predictive encoding program according to oneembodiment causes a computer to function as: (a) a region division unitfor dividing an input image into a plurality of regions; (b) aprediction information estimation unit for producing a prediction signalof a target region among the plurality of regions from a reconstructedsignal and obtaining prediction information that is used to produce theprediction signal, as prediction information associated with the targetregion; (c) a prediction information encoding unit for encoding theprediction information associated with the target region; (d) a decisionunit for making a comparison of the prediction information associatedwith the target region and prediction information associated with aneighbouring region located adjacent to the target region and deciding,based on a result of the comparison, whether the prediction informationassociated with the neighbouring region can be used to produce theprediction signal of the target region; (e) a region width determinationunit for, when it is decided by the decision unit that the predictioninformation associated with the neighbouring region can be used toproduce the prediction signal of the target region, determining a regionwidth of a partition that is included in the target region and where theprediction information associated with the neighbouring region is usedto produce the prediction signal; (f) a region width encoding unit forencoding information identifying the region width; (g) a predictionsignal production unit for producing the prediction signal of the targetregion from the reconstructed signal by using at least one of theprediction information associated with the target region, the predictioninformation associated with the neighbouring region, and the regionwidth; (h) a residual signal production unit for producing a residualsignal indicative of a difference between the prediction signal of thetarget region and the original signal of the target region; (i) aresidual signal encoding unit for encoding the residual signal; (j) aresidual signal restoration unit for producing a decoded residual signalby decoding encoded data of the residual signal; (k) an adding unit forproducing a reconstructed signal of the target region by adding theprediction signal to the decoded residual signal; and (1) a storage unitfor storing the reconstructed signal of the target region.

According to an encoding aspect of the image predictiveencoding/decoding system, when the prediction information of theneighbouring region can be used, the prediction signal of the partitionin the target region may be produced by using the prediction informationof the neighbouring region. Therefore, prediction error of the targetregion where an edge of an image exists can be reduced. In addition,since the prediction information of the neighbouring region may be usedto produce the prediction signal of the partition in the target region,it is possible to suppress an increase in an amount of predictioninformation.

In one embodiment, when it is decided that the prediction informationassociated with the target region and the prediction informationassociated with the neighbouring region are the same, similar,substantially similar, matching, or identical, it may be decided thatthe prediction information associated with the neighbouring region isnot used to produce the prediction signal of the target region. This isbecause when the prediction information associated with the targetregion and the prediction information associated with the neighbouringregion are the same, a reduction in the prediction error of the targetregion is not achieved.

In one embodiment, when it is decided that a combination of theprediction information associated with the target region and theprediction information associated with the neighbouring region fails tosatisfy a predetermined condition, it may be decided that the predictioninformation associated with the neighbouring region is not used toproduce the prediction signal of the target region.

In an encoding aspect of the image predictive encoding/decoding system,when it is decided that the prediction information associated with theneighbouring region is not used to produce the prediction signal of thetarget region, encoded data of the region width associated with thetarget region may not be output. The code amount is thereby reduced.

In one embodiment, the neighbouring region may be at least twoneighbouring regions. The at least two neighbouring regions may beadjacent or contiguous to the same side, or different sides of thetarget region, such as a first side and a second side of the targetregion, where a side may constitute a surface, a perimeter, border, orany other boundary or periphery of the target region. For example, oneof the at least two neighbouring regions may be on the left side of thetarget region, and a second of the two neighbouring regions may be onanother side, such as the top of the target region. In such a case, whenit is decided that prediction information associated with both of the atleast two neighbouring regions can be used to produce the predictionsignal of the target region, identification information that identifiesan neighbouring region having the prediction information to be used toproduce the prediction signal of the target region from the at least twoneighbouring regions, can be encoded. According to such a feature, it ispossible to produce the prediction signal of the partition from anoptimal neighbouring region out of the at least two neighbouringregions, thereby further reductions in the prediction error may beachieved.

Another aspect of the image predictive encoding/decoding system relatesto decoding of an image. An image predictive decoding device accordingto one embodiment includes: (a) data analysis means for extracting, fromcompressed data which has been produced by dividing an image into aplurality of regions and encoding the regions, encoded data ofprediction information that has been used to produce a prediction signalof a target region, encoded data of information identifying a regionwidth of a partition in the target region where prediction informationassociated with an neighbouring region located adjacent to the targetregion has been used to produce the prediction signal, and encoded dataof a residual signal; (b) prediction information decoding means forrestoring the prediction information associated with the target regionby decoding the encoded data of the prediction information; (c) decisionmeans for making a comparison of the prediction information associatedwith the target region and the prediction information associated withthe neighbouring region, and deciding, based on a result of thecomparison, whether the prediction information associated with theneighbouring region can be used to produce the prediction signal of thetarget region; (d) region width decoding means for, when it is decidedby the decision means that the prediction information associated withthe neighbouring region can be used to produce the prediction signal ofthe target region, restoring the region width by decoding the encodeddata of the information identifying the region width; (e) predictionsignal production means for producing the prediction signal of thetarget region from a reconstructed signal by using at least one of theprediction information associated with the target region, the predictioninformation associated with the neighbouring region, and the regionwidth; (f) residual signal restoration means for restoring a decodedresidual signal of the target region from the encoded data of theresidual signal; (g) adding means for producing a reconstructed signalof the target region by adding the prediction signal of the targetregion to the decoded residual signal; and (h) storage means for storingthe reconstructed signal of the target region.

In addition, an image predictive decoding method according to oneembodiment includes: (a) a data analysis step for extracting, fromcompressed data which has been generated by dividing an image into aplurality of regions and encoding the regions, encoded data ofprediction information that has been used to produce a prediction signalof a target region, encoded data of information identifying a regionwidth of a partition in the target region where prediction informationassociated with an neighbouring region located adjacent to the targetregion has been used to produce the prediction signal, and encoded dataof a residual signal; (b) a prediction information decoding step forrestoring the prediction information associated with the target regionby decoding the encoded data of the prediction information; (c) adecision step for making a comparison of the prediction informationassociated with the target region and the prediction informationassociated with the neighbouring region, and deciding, based on a resultof the comparison, whether the prediction information associated withthe neighbouring region can be used to produce the prediction signal ofthe target region; (d) a region width decoding step for, when it isdecided in the decision step that the prediction information associatedwith the neighbouring region can be used to produce the predictionsignal of the target region, restoring the region width by decoding theencoded data of the information identifying the region width; (e) aprediction signal production step for producing the prediction signal ofthe target region from a reconstructed signal by using at least one ofthe prediction information associated with the target region, theprediction information associated with the neighbouring region, and theregion width; (f) a residual signal restoration step for restoring adecoded residual signal of the target region from the encoded data ofthe residual signal; (g) a reconstructed signal production step forproducing a reconstructed signal of the target region by adding theprediction signal of the target region to the decoded residual signal;and (h) a storage step for storing the reconstructed signal of thetarget region.

Furthermore, an image predictive decoding program according to oneembodiment causes a computer to function as: (a) data analysis means forextracting, from compressed data which has been produced by dividing animage into a plurality of regions and encoding the regions, encoded dataof prediction information that has been used to produce a predictionsignal of a target region; encoded data of information identifying aregion width of a partition in the target region where predictioninformation associated with a neighbouring region located adjacent tothe target region has been used to produce the prediction signal; andencoded data of a residual signal; (b) prediction information decodingmeans for restoring the prediction information associated with thetarget region by decoding the encoded data of the predictioninformation; (c) decision means for making a comparison of theprediction information associated with the target region and theprediction information associated with the neighbouring region anddeciding, based on a result of the comparison, whether the predictioninformation associated with the neighbouring region can be used toproduce the prediction signal of the target region; (d) region widthdecoding means for, when it is decided by the decision means that theprediction information associated with the neighbouring region can beused to produce the prediction signal of the target region, restoringthe region width by decoding the encoded data of the informationidentifying the region width; (e) prediction signal production means forproducing the prediction signal of the target region from areconstructed signal by using at least one of the prediction informationassociated with the target region, the prediction information associatedwith the neighbouring region, and the region width; (f) residual signalrestoration means for restoring a decoded residual signal of the targetregion from the encoded data of the residual signal; (g) adding meansfor producing a reconstructed signal of the target region by adding theprediction signal of the target region to the decoded residual signal;and (h) storage means for storing the reconstructed signal of the targetregion as the reconstructed signal. The image predictiveencoding/decoding system according to such decoding enables the systemto preferably reproduce an image from the compressed data produced byencoding such as described above.

In one embodiment, when it is decided that the prediction informationassociated with the target region and the prediction informationassociated with the neighbouring region match, or are the same, or aresubstantially similar, it may be decided that the prediction informationassociated with the neighbouring region fails to be used to produce theprediction signal of the target region. In addition, when it is decidedthat a combination of the prediction information associated with thetarget region and the prediction information associated with theneighbouring region fails to satisfy a predetermined condition, it maybe decided that the prediction information associated with theneighbouring region will not be used to produce the prediction signal ofthe target region.

In one embodiment, when it is decided that the prediction informationassociated with the neighbouring region fails is not used to produce theprediction signal of the target region, the region width associated withthe target region may be set to a predetermined value, such as zero.

In one embodiment, the neighbouring region may be two or moreneighbouring regions. The two or more neighbouring regions may beadjacent one or more sides of target region, for example, a first of thetwo or more neighbouring regions may be on the left of the targetregion, and a second of the two or more neighbouring regions may be ontop of the target region. The sides of the target region may constitutea surface, a perimeter, border, or any other boundary or periphery ofthe target region. In such case, when it is decided that both predictioninformation associated with the two or more neighbouring regions can beused to produce the prediction signal of the target region, the regionwidth decoding means can decode identification information thatidentifies an neighbouring region having the prediction information tobe used to produce the prediction signal of the target region from thetwo or more neighbouring regions.

The image predictive encoding/decoding system may include an imagepredictive encoding device, an image predictive encoding method and animage predictive encoding program that can efficiently encode an imageby suppressing an increase in prediction information and reducingprediction error of a target block. In addition, the image predictiveencoding/decoding system may include an image predictive decodingdevice, an image predictive decoding method and an image predictivedecoding program.

Other systems, methods, features and advantages will be, or will become,apparent to one with skill in the art upon examination of the followingfigures and detailed description. It is intended that all suchadditional systems, methods, features and advantages be included withinthis description, be within the scope of the invention, and be protectedby the following claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing an example of an image predictive encodingdevice according to one embodiment;

FIG. 2 is a diagram illustrating an example of a partition in a targetblock where a prediction signal is produced by using predictioninformation of a neighbouring block;

FIG. 3 is a flowchart showing example procedures of an image predictiveencoding method according to one embodiment;

FIG. 4 is a detailed flowchart of an example of step S108 in FIG. 3;

FIG. 5 is a detailed flowchart of an example of step S202 in FIG. 4;

FIG. 6 is a detailed flowchart of an example of step S110 in FIG. 3;

FIG. 7 is a diagram showing an example of an image predictive decodingdevice according to one embodiment;

FIG. 8 is a flowchart of an example of an image predictive decodingmethod according to one embodiment;

FIG. 9 is a detailed flowchart of an example of step S508 in FIG. 8;

FIG. 10 is a diagram illustrating another example of the neighbouringblock;

FIG. 11 is a flowchart showing detailed procedures of another example ofstep S108 in FIG. 3;

FIG. 12 is a flowchart showing detailed procedures of another example ofstep S508 in FIG. 8;

FIG. 13 is a diagram illustrating another example of the partition inthe target block where the prediction signal is produced by using theprediction information of the neighbouring block;

FIGS. 14A and 14B are diagrams showing another example of the partition;

FIGS. 15A through 15C are diagrams showing other examples of the targetblock and the neighbouring block;

FIG. 16 is a diagram showing an image predictive encoding programaccording to one embodiment;

FIG. 17 is a diagram showing an image predictive decoding programaccording to one embodiment;

FIG. 18 is a diagram showing an example hardware structure of a computerfor executing a program stored in a record medium;

FIG. 19 is a perspective view of the computer for executing the programstored in the record medium;

FIGS. 20A through 201 are schematic views describing an example of anintra-picture prediction method; and

FIGS. 21A and 21B are schematic views describing an example of blockmatching.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Example embodiments of the image predictive encoding/decoding system aredescribed in detail below with reference to the drawings. In eachdrawing, parts that are the same or equivalent are labeled with the samereference numerals.

In image predictive encoding/decoding system, encoding processing anddecoding processing are performed after dividing an image serving as anencoding target into a plurality of blocks. In intra-picture predictionencoding, a prediction signal of a target block is produced by using anadjacent reconstructed image signal within the same picture where thetarget block is included. The reconstructed image signal is generated byrestoring compressed image data. Next, in the intra-picture predictionencoding, a differential signal is generated by subtracting theprediction signal from a signal of the target block, and thedifferential signal is encoded. In inter-picture prediction encoding,referring to the reconstructed image signal within a different picturefrom the picture where the target block is included, motion compensationis performed, and a prediction signal is thereby produced. Next, in theinter-picture prediction encoding, the prediction signal is subtractedfrom the signal of the target block so as to produce a differentialsignal, and the differential signal is encoded.

For example, intra-picture prediction encoding may include a method inwhich the prediction signal is produced by extrapolating, in apredetermined direction, reconstructed pixel values (reconstructedsignals) of pixels located neighbouring, or adjacent to a block servingas an encoding target. FIG. 20 is a schematic view describing an exampleof the intra-picture prediction method. FIG. 20A shows the intra-pictureprediction method in which extrapolation is performed in a verticaldirection. In FIG. 20A, a 4×4 pixel target block 802 is the exampletarget block serving as an encoding target. A pixel group 801 composedof pixels A to M located neighbouring, or adjacent to a boundary of thetarget block 802 is a neighbouring region, and is an image signal thathas been reconstructed in the past process. In prediction shown in FIG.20A, pixel values of the adjacent pixels A to D located directly abovethe target block 802 are extrapolated downwards so as to produce aprediction signal.

FIG. 20B shows an intra-picture prediction method in which extrapolationis performed in a horizontal direction. In the prediction shown in FIG.20B, a prediction signal is produced by extrapolating pixel values ofreconstructed pixels Ito L located on the left of the target block 802rightward.

In the intra-picture prediction method, the prediction signal having thelowest difference from the original signal of the target block may betaken to be the optimal prediction signal, from among the nineprediction signals produced by the methods shown in A-I of FIG. 20.

In inter-picture prediction encoding, a prediction signal is produced bysearching for a signal resembling the original signal of the blockserving as the encoding target, from reconstructed pictures. In theinter-picture prediction encoding, a motion vector and a residual signalbetween the original signal and the prediction signal of the targetblock are encoded. The motion vector is a vector indicating a spatialdisplacement amount between the target block and a region where thesearched signal is located. The technique of searching for the motionvector for each block, in this way, may be described as block matching.

FIG. 21 is a schematic view describing an example of block matching. InFIG. 21, a reconstructed picture 903 is shown in FIG. 21A and a picture901 including a target block 902 is shown in FIG. 21B. Here, a region904 in the picture 903 is a region that is in the same spatial positionas the target block 902. In block matching, a search range 905surrounding the region 904 is set, and a region 906 that has the lowestsum of absolute differences with respect to the original signal of thetarget block 902 is detected from the search range. The signal of theregion 906 becomes a prediction signal, and a vector indicating thedisplacement amount from the region 904 to the region 906 is detected asa motion vector 907.

In block matching, there may also be a method in which a plurality ofreference pictures 903 are prepared, and the reference picture forperforming the block matching is selected for each target block, andreference picture selection information is detected. In order toaccommodate local feature changes in images, a plurality of predictiontypes with different block sizes for encoding the motion vector may beprepared.

In compression encoding of moving image data, each picture (frame orfield) can be encoded in any sequence. Therefore, there are a number ofapproaches, such as three, for an encoding order in the inter-pictureprediction that produces a prediction signal with reference toreconstructed pictures. For example, a first approach is a forwardprediction that produces a prediction signal with reference toreconstructed pictures in the past in a reproduction order. A secondapproach is a backward prediction that produces a prediction signal withreference to reconstructed pictures in the future in a display order. Athird approach is a bidirectional prediction that performs both forwardprediction and backward prediction so as to average the two predictionsignals.

FIG. 1 is a diagram showing an example image predictive encoding deviceaccording to one embodiment of the image predictive encoding/decodingsystem. An image predictive encoding device 100 shown in FIG. 1 includesa plurality of modules, units and/or components. The picture predictingencoding device 100 may be a computing device or computer, including forexample software, hardware, or a combination of hardware and software,as described later, capable of performing the described functionality.The image prediction encoding device 100 may be one or more separatesystems or devices, may be one or more systems or devices included inthe image encoding/decoding system, or may be combined with othersystems or devices within the image predictive encoding/decoding system.In other examples, fewer or additional blocks may be used to illustratethe functionality of the image prediction encoding device 100. Themodules, units and/or components include an input terminal 102, a blockdivision unit 104, a prediction signal generator 106, a frame memory108, a subtractor 110, a transformer 112, a quantizer 114, an inversequantizer 116, an inverse transformer 118, an adder 120, a quantizedtransformed coefficient encoder 122, an output terminal 124, aprediction information estimator 126, a prediction information memory128, a decision unit 130, a prediction information encoder 132, a regionwidth determiner 134 and a region width encoder 136. The transformer112, the quantizer 114, and the quantized transformed coefficientencoder 122 function as residual signal encoding means, or residualsignal encoder unit, while the inverse quantizer 116 and the inversetransformer 118 function as residual signal restoration means, or aresidual signal restoration unit. Accordingly, all of the functionalityincluded in the image predictive encoding device 100 may be modules,components, and/or units. The term “module” “component” or “unit” may bedefined to include one or more executable parts of the image predictiveencoding/decoding system. As described herein, the modules, components,and/or units are defined to include software, hardware or somecombination thereof executable by a processor (described later).Software included in the modules, components, and/or units may includeinstructions stored in memory or a computer readable medium that areexecutable by the processor, or any other processor. Hardware includedin the modules, component, and/or units may include various devices,components, circuits, gates, circuit boards, and the like that areexecutable, directed, and/or controlled for performance by theprocessor. In other examples, fewer or additional modules, units and/orcomponents may be used to describe the functionality of the imagepredictive encoding device 100.

Each component, module and/or unit of the image predictive encodingdevice 100 will be described below. The input terminal 102 is a terminalfor inputting a signal of a moving picture. The signal of the movingpicture is a signal that includes a plurality of images. The inputterminal 102 is connected through a line L102 to the block division unit104.

The block division unit 104, or region division unit, divides the imagethat is included in the signal of the moving picture into a plurality ofregions. Specifically, the block division unit 104 may sequentiallyselect the plurality of images that are included in the signal of themoving picture as an encoding target image. The block division unit 104divides the selected image into a plurality of regions. In the presentembodiment, the region is an 8×8 pixel block. However, blocks withdifferent sizes and/or shapes may be used as the region. The blockdivision unit 104 is connected through a line L104 to the predictioninformation estimator 126.

The prediction information estimator 126, or prediction informationestimator unit, detects prediction information to produce a predictionsignal of a target region (a target block) that is the target ofencoding processing. As for a method for producing predictioninformation, the examples of previously described intra-pictureprediction or inter-picture prediction that was described in thebackground art, is applicable. The image predictive encoding/decodingsystem, however, is not limited to such prediction methods, and anyother prediction methods may be used. The description below is given inthe case where the block matching shown in FIG. 21 is performed in aprediction process. When block matching is used, the predictioninformation includes motion vectors, reference picture selectioninformation and the like, which is hereafter referred to as “predictioninformation.” Hereinafter, prediction information that is detected toproduce the prediction signal of the target block is referred to as“prediction information associated with a target block”. The predictioninformation estimator 126 is connected through a line L126 a and a lineL126 b to the prediction information memory 128 and the predictioninformation encoder 132, respectively.

The prediction information memory 128 receives the predictioninformation through the line L126 a from the prediction informationestimator 126 and stores the prediction information. The predictioninformation memory 128 is connected through a line L128 to the decisionunit 130.

The prediction information encoder 132, or prediction informationencoder unit, receives the prediction information through the line L126b from the prediction information estimator 126. The predictioninformation encoder 132 entropy-codes the received predictioninformation to produce encoded data and outputs the encoded data througha line L132 to the output terminal 124. Examples of entropy encodinginclude arithmetic coding, variable-length coding and the like, but theimage predictor encoding/decoding system is not limited to such entropyencoding methods.

The decision unit 130 receives the prediction information associatedwith the target block and the prediction information associated with aneighbouring block through the line L128 from the prediction informationmemory 128. The neighbouring block is a neighbouring region locatedadjacent to the target block and is an already encoded region. Thedecision unit 130 compares the prediction information associated withthe target block against the prediction information associated with theneighbouring block, and decides whether the prediction informationassociated with the neighbouring block can be used to produce theprediction signal of the target block.

Specifically, the decision unit 130 compares the prediction informationassociated with the target block against the prediction informationassociated with the neighbouring block, and when two or more pieces ofprediction information substantially coincide, or match, it decides thatthe prediction information associated with the neighbouring block willnot be used to produce the prediction signal of the target block. Thisis because, when the at least two pieces of prediction informationsubstantially coincide, or match, the prediction signal of a partitionof the target block produced by using the prediction informationassociated with the neighbouring block may achieve a similar, or thesame result as the prediction signal produced by using the predictioninformation associated with the target block. That is, reduction inprediction error cannot be expected.

On the other hand, when the two or more pieces of prediction informationare different, the decision unit 130 decides that the predictioninformation associated with the neighbouring block can be used toproduce the prediction signal of the target block. The decision unit 130is connected through a line L130 to the region width determiner 134 andthe region width encoder 136, or region width encoding unit, and acomparison (decision) result by the decision unit 130 is output throughthe line L130 to the region width determiner 134 and the region widthencoder 136. Hereinafter, the decision result of a case when theprediction information associated with the neighbouring block will notbe used to produce the prediction signal of the target block, isreferred to as the decision result indicating “unusable”, while thedecision result of a case when the prediction information associatedwith the neighbouring block can be used to produce the prediction signalof the target block, is referred to as the decision result indicating“usable”. Operations of the decision unit 130 are described in detailbelow.

The region width determiner 134, or region width determination unit,receives the decision result through the line L130 from the decisionunit 130. When the decision result indicates “usable”, the region widthdeterminer 134 determines a region width of the partition of the targetblock where the prediction signal is produced by using the predictioninformation associated with the neighbouring block. Therefore, theregion width determiner 134 receives the prediction informationassociated with the target block and the prediction informationassociated with the neighbouring block through a line L128 a from theprediction information memory 128. Furthermore, the region widthdeterminer 134 receives a reconstructed signal from the frame memory 108and receives an original signal of the target block from the blockdivision unit 104.

FIG. 2 is a diagram describing the partition of the target block wherethe prediction signal is produced by using the prediction information ofthe neighbouring block. FIG. 2 shows a case where an neighbouring blockB1 on the edge of the target block, such as on the left of a targetblock Bt serves as the neighbouring block, but the neighbouring block inthe image predictor encoding/decoding system may be an neighbouringblock on a second side, such as the top of the target block or bothneighbouring blocks, on a first and a second side, such as on the leftand on the top of the target block, or blocks adjacent any one or moresides of the target block. There are cases that neighbouring blocks onthe right and on the bottom of the target block can be used as theneighbouring block. As described herein, the edges of the target blockmay be a surface, a perimeter, border, or any other boundary orperiphery of the target region.

As shown in FIG. 2, the target block Bt and the neighbouring block B1are a 8×8 pixel block. In FIG. 2, a top-left pixel position (horizontalposition, vertical position) is represented by (0, 0), while abottom-right pixel position (horizontal position, vertical position) isrepresented by (7, 7). A partition R2 shown in FIG. 2 is a region wherethe prediction information of the neighbouring block B11 is used toproduce the prediction signal and a region width thereof is w in ahorizontal direction. That is, the partition R2 is surrounded by fourpixel positions of (0, 0), (w-1, 0), (0, 7) and (w-1, 7). A partition R1is a region where the prediction information associated with the targetblock is used to produce the prediction signal.

In the present embodiment, the region width can be set from 0 to 8pixels with one pixel increment. The region width determiner 134 of thepresent embodiment produces the prediction signal of the target blockwith respect to each of 8 settable region widths and selects the regionwidth having the lowest absolute sum of the prediction error or thelowest square sum thereof. The process is performed by acquiring anoriginal signal of the target block and the prediction informationassociated with the target block and the prediction informationassociated with the neighbouring block from the block division unit 104and the prediction information memory 128, respectively and by producingthe prediction signal of the target block, based on these pieces ofprediction information and the region width, from the reconstructedsignal that is stored in the frame memory 108. A method for determiningthe region width and candidates for the settable region width are notparticularly limited. For example, the settable region widths may bepixel widths that are specified by multiples of 2, and can take any oneor more width. Additionally, a plurality of settable region widths areprepared and selection information may be encoded for each sequenceunit, each frame unit or each block unit.

The region width determiner 134 is connected through a line L134 a and aline L134 b to the region width encoder 136 and the prediction signalgenerator 106, respectively. The region width determiner 134 outputs thedetermined region width (information identifying the region width)through the line L134 a and the line L134 b to the region width encoder136 and the prediction signal generator 106.

When the decision result received from the decision unit 130 indicates“usable”, the region width encoder 136 entropy-codes the region widthreceived through the line L134 a to produce encoded data. The regionwidth encoder 136 may use an entropy-coding method, such as arithmeticcoding or variable-length coding, but the image predictorencoding/decoding system is not limited to such encoding methods.

The region width encoder 136 is connected through a line L136 to theoutput terminal 124, and the encoded data produced by the region widthencoder 136 is output through the line L136 to the output terminal 124.

The prediction signal generator 106, or prediction signal productionunit, receives two pieces of prediction information associated with thetarget block and the neighbouring block through a line L128 b from theprediction information memory 128. Additionally, the prediction signalgenerator 106 receives the region width through the line L134 b from theregion width determiner 134, and receives the reconstructed signalthrough a line L108 from the frame memory 108. The prediction signalgenerator 106 may use one or more of the at least two pieces ofprediction information and the region width received to produce theprediction signal of the target block from the reconstructed signal.Examples of a method for producing the prediction signal are describedbelow. The prediction signal generator 106 is connected through a lineL106 to the subtractor 110. The prediction signal produced by theprediction signal generator 106 is output through the line L106 to thesubtractor 110.

The subtractor 110 is connected through a line L104 b to the blockdivision unit 104. The subtractor 110 subtracts the prediction signal ofthe target block produced by the prediction signal generator 106 fromthe original signal of the target block, which is received through theline L104 b from the block division unit 104. A residual signal isproduced through such subtraction. The subtractor 110 is connectedthrough a line L110 to the transformer 112 and the residual signal isoutput through the line L110 to the transformer 112.

The transformer 112 applies a discrete cosine transform to the inputresidual signal to produce transformed coefficients. The quantizer 114receives the transformed coefficients through a line L112 from thetransformer 112. The quantizer 114 quantizes the transformedcoefficients to produce quantized transformed coefficients. Thequantized transformed coefficient encoder 122 receives the quantizedtransformed coefficients through a line L114 from the quantizer 114 andentropy-codes the quantized transformed coefficients to produce encodeddata. The quantized transformed coefficient encoder 122 outputs theencoded data produced through a line L122 to the output terminal 124. Asan entropy-coding method for the quantized transformed coefficientencoder 122, arithmetic coding or variable-length coding may be used,but the image predictor encoding/decoding system is not limited to suchcoding methods.

The output terminal 124 collectively outputs the encoded data receivedfrom the prediction information encoder 132, the region width encoder136 and the quantized transformed coefficient encoder 122, to modules ordevices outside, or external to, the image predictive encoding device100.

The inverse quantizer 116 receives the quantized transformedcoefficients through a line L114 b from the quantizer 114. The inversequantizer 116 inversely quantizes the received quantized transformedcoefficients to restore transformed coefficients. The inversetransformer 118 receives the transformed coefficients through a lineL116 from the inverse quantizer 116 and applies an inverse discretecosine transform to the transformed coefficients so as to restore aresidual signal (decoded residual signal). The adder 120, or adder unit,receives the decoded residual signal through a line L118 from theinverse transformer 118 and receives the prediction signal through aline L106 b from the prediction signal generator 106. The adder 120 addsthe received decoded residual signal to the prediction signal toreproduce a signal of the target block (reconstructed signal). Thereconstructed signal produced by the adder 120 is output through a lineL120 to the frame memory 108, or storage unit, and is stored in theframe memory 108 as the reconstructed signal. In other examples, thereconstructed signal may be store in any other storage unit internal to,or external to the image predictive encoding device 100.

The present embodiment uses the transformer 112 and the inversetransformer 118, but another transform process may be used asalternatives of these transformers. In addition, the transformer 112 andthe inverse transformer 118 are not indispensable. In this way, in orderto be used for producing the prediction signal of the subsequent targetblock, the reconstructed signal of the encoded target block is restoredin an inverse process and stored in the frame memory 108.

Moreover, the structure of the encoder is not limited to the one shownin FIG. 1. For example, the decision unit 130 and the predictioninformation memory 128 may be included in the prediction signalgenerator 106. In addition, the region width determiner 134 may beincluded in the prediction information estimator 126.

With reference to operations of the image predictive encoding device100, an image predictive encoding method of one embodiment is describedbelow. In addition, detailed operations of the decision unit 130, theregion width determiner 134 and the prediction signal generator 106 aredescribed.

FIG. 3 is a flowchart showing procedures of the image predictiveencoding method according to one example embodiment. As shown in FIG. 3,in the present image predictive encoding method, first in step S100, theblock division unit 104 divides an encoding target image into aplurality of blocks. Then in step S102, one block is selected from theplurality of blocks as an encoding target block.

Then in step S104, the prediction information estimator 126 determinesprediction information of the target block. The prediction informationis encoded in the following step S106 by the prediction informationencoder 132.

Next, the present image predictive encoding method proceeds to stepS108. FIG. 4 is a detailed flowchart of step S108 in FIG. 3. In theprocess of step S108, first in step S200, two or more pieces ofprediction information associated with the target block and theneighbouring block are input in the decision unit 130. Then in stepS202, the decision unit 130 decides whether the prediction informationof the neighbouring block can be used to produce the prediction signalof the target block.

FIG. 5 is a detailed flowchart of step S202 in FIG. 4. As shown in FIG.5, in the process of step S202, first in step S300, the decision unit130 decides whether the at least two pieces of prediction informationassociated with the target block and the neighbouring block coincide.When the decision in step S300 is true (Yes), that is when the at leasttwo pieces of prediction information associated with the target blockand the neighbouring block coincide, the decision unit 130 outputs adecision result indicating “unusable” in step S302.

On the other hand, when the decision in step S300 is false (No), theprocess proceeds to step S304. In step S304, the decision unit 130decides whether the prediction information associated with theneighbouring block is in a usable state to produce the prediction signalof the target block. When the decision in step S304 is true (Yes), thedecision unit 130 outputs the decision result indicating “usable” in thefollowing step S306. On the other hand, when the decision in step S304is false (No), the decision unit 130 conducts the process of step S302described above.

When it is decided that the prediction information associated with theneighbouring block is in an unusable state in step S304, there are caseswhere (1) the neighbouring block is outside a picture; (2) a combinationof the prediction information of the target block and the predictioninformation of the neighbouring block is not approved; and the like.

In this way, the decision unit 130 decides, in accordance with apredetermined rule, whether to use the prediction information associatedwith the neighbouring block to produce the prediction signal of thepartition of the target region. The rule is not required to betransmitted, if the encoder and the decoder share the information inadvance, but it may be encoded and transmitted. For example, there is amethod in which a plurality of such rules are prepared and which rule tobe applied is transmitted for each frame unit, each sequence unit, oreach block unit.

Referring to FIG. 4 again, next, the present image predictive encodingmethod proceeds to step S204. In step S204, the region width determiner134 refers to the decision result of the decision unit 130 and decideswhether the decision result indicates “usable” or not. When the decisionresult of the decision unit 130 indicates “unusable”, the process ofstep S108 ends.

On the other hand, when the decision result of the decision unit 130indicates “usable”, the region width determiner 134 selects, in thefollowing step S206, the region width of the partition of the targetregion to be predicted by using the prediction information associatedwith the neighbouring block, from among candidates prepared in advance.Then in step S208, the region width encoder 136 encodes the determinedregion width.

Referring to FIG. 3 again, the process proceeds from step S108 to stepS110. In step S110, the prediction signal generator 106 may use the atleast two pieces of prediction information associated with the targetblock and the neighbouring block, and the region width determined by theregion width determiner 134, to produce the prediction signal of thetarget block from the reconstructed signal stored in the frame memory108.

One example of detailed operations of the prediction signal generator106 in step S110 is described below. FIG. 6 is a detailed flowchart ofstep S110 in FIG. 3. FIG. 6 shows operations of the prediction signalgenerator 106, when, as shown in FIG. 2, the prediction signal of apartition R2 in a 8×8 pixel target block is produced by using theprediction information associated with the neighbouring block on theleft, or neighbouring, a side of the target block.

As shown in FIG. 6, first in step S400, the prediction signal generator106 acquires prediction information Pt associated with the target blockand prediction information Pn associated with the neighbouring block.Then in step S402, the prediction signal generator 106 acquires a regionwidth w from the region width determiner 134.

Next in step S404, the prediction signal generator 106 may use at leastone of the prediction information Pt and the region width w to producethe prediction signal of the partition R1 in the target block shown inFIG. 2 from the reconstructed signal. Next in step S406, the predictionsignal generator 106 may use at least one of the prediction informationPn and the region width w to produce a prediction signal of thepartition R2 in the target block from the reconstructed signal. In theexample shown in FIG. 2, when the region width w is 0, step S406 can beomitted. In addition, when the region width is 8, step S404 can beomitted.

Referring to FIG. 3 again, the image predictive encoding method proceedsto step S112. In step S112, the subtractor 110 uses the original signaland the prediction signal of the target block to produce a residualsignal. In the following step S114, the transformer 112, the quantizer114 and the quantized transformed coefficient encoder 122 may transformand encode the residual signal to produce encoded data.

Then in step S116, the inverse quantizer 116 and the inverse transformer118 may restore a decoded residual signal from quantized transformedcoefficients. In the following step S118, the adder 120 adds the decodedresidual signal to the prediction signal to produce a reconstructedsignal. Then in step S120, the reconstructed signal is stored in theframe memory 108 as the reconstructed signal.

Next in step S122, whether all blocks are processed as the target blockis checked and when the process on all blocks is uncompleted, one ofunprocessed blocks is selected as the target block and the process fromstep S102 is performed. On the other hand, when the process on allblocks is completed, the process of the present image predictiveencoding method ends.

An image predictive decoding device according to one embodiment isdescribed below. FIG. 7 is a diagram showing the image predictivedecoding device according to one example embodiment. An image predictivedecoding device 200 shown in FIG. 7 is provided with a plurality ofmodules, units, and/or components. The image predictive decoding device200 may be a computing device or computer, including for examplesoftware, hardware, or a combination of hardware and software, asdescribed later, capable of performing the described functionality. Theimage predictive decoding device 200 may be one or more separate systemsor devices, may be one or more systems or devices included in the imagepredictive encoding/decoding system, or may be combined with othersystems or devices within the image predictive encoding/decoding system.In other examples, fewer or additional blocks may be used to illustratethe functionality of the image predictive decoding device 200. Themodules, units and/or components of the image predictive decoding device200 may include an input terminal 202, a data analyzer 204, an inversequantizer 206, an inverse transformer 208, an adder 210, an outputterminal 212, a quantized transformed coefficient decoder 214, aprediction information decoder 216, a region width decoder 218, theframe memory 108, the prediction signal generator 106, the predictioninformation memory 128, and the decision unit 130. The inverse quantizer206, the inverse transformer 208 and the quantized transformedcoefficient decoder 214 function as residual signal restoration unit.For decoding means including the inverse quantizer 206 and the inversetransformer 208, alternatives may be used. In addition, the inversetransformer 208 may be eliminated. The functionality included in theimage predictive decoding device 200 may be modules, components and/orunits. The term “module” or “component” or “unit” may be defined toinclude one or more executable parts of the image predictiveencoding/decoding system. As described herein, the modules and/or unitsare defined to include software, hardware or some combination thereofexecutable by a processor (described later). Software included in themodules and/or units may include instructions stored in memory or acomputer readable medium that are executable by the processor, or anyother processor. Hardware included in the modules and/or units mayinclude various devices, components, circuits, gates, circuit boards,and the like that are executable, directed, and/or controlled forperformance by the processor.

Each component, unit or module of the image predictive decoding device200 is described in detail below. The input terminal 202 inputs data,such as compressed data that has been compression-encoded by the imagepredictive encoding device 100 (or the image predictive encoding method)described above. The compressed data includes, with respect to each of aplurality of blocks in an image, encoded data of quantized transformedcoefficients produced by transform-quantizing and entropy-coding aresidual signal; encoded data of prediction information for producing aprediction signal; and encoded data of a region width of a partition inthe block where the prediction signal is produced by using theprediction information associated with a neighbouring block locatedneighbouring, adjacent to, or beside, a target block. In the presentembodiment, the prediction information includes a motion vector and areference picture number and the like. The input terminal 202 isconnected via a line L202 to the data analyzer 204.

The data analyzer 204, or data analysis unit, receives the compresseddata through the line L202 from the input terminal 202. The dataanalyzer 204 analyzes the received compressed data and separates thecompressed data, with respect to a decoding target block, into theencoded data of the quantized transformed coefficients; the encoded dataof the prediction information; and the encoded data of the region width.The data analyzer 204 outputs the encoded data of the region widththrough a line L204 a to the region width decoder 218; or region widthdecoding unit, outputs the encoded data of the prediction informationthrough a line L204 b to the prediction information decoder 216; orprediction information decoding unit, and outputs the encoded data ofthe quantized transformed coefficients through a line L204 c to thequantized transformed coefficient decoder 214.

The prediction information decoder 216 entropy-decodes the encoded dataof the prediction information associated with the target block to obtainprediction information. The prediction information decoder 216 isconnected through a line L216 to the prediction information memory 128.The prediction information produced by the prediction informationdecoder 216 is stored through the line L216 in the predictioninformation memory 128. The prediction information memory 128 isconnected through the line L128 a and the line L128 b to the decisionunit 130 and the prediction signal generator 106, respectively.

The decision unit 130 has similar functionality to the decision unit 130of the encoding device shown in FIG. 1. That is, the decision unit 130compares the prediction information associated with the target blockagainst the prediction information associated with the neighbouringblock located adjacent to the target block, and decides whether theprediction information associated with the neighbouring block can beused when producing the prediction signal of the target block.

Specifically, the decision unit 130 compares at least two pieces ofprediction information associated with the target block and theneighbouring block located adjacent with each other, and when the atleast two pieces of prediction information coincide, it decides that theprediction information associated with the neighbouring block will notbe used to produce the prediction signal of the target block. That is,in such case, the decision unit 130 outputs a decision result indicating“unusable”. On the other hand, when the at least two pieces ofprediction information are different, the decision unit 130 outputs thedecision result indicating “usable”. The decision unit 130 is connectedthrough the line L130 to the region width decoder 218. The decisionresult by the decision unit 130 is output through the line L130 to theregion width decoder 218. Since a detailed example process flow of theprocess of the decision unit 130 was described with reference to FIG. 5,the detailed description is omitted here.

The region width decoder 218 entropy-decodes, based on the decisionresult received through the L130 from the decision unit 130, the inputencoded data of the region width to restore the region width. That is,when the decision result indicates “usable”, the region width decoder218 decodes the encoded data of the region width to restore the regionwidth. On the other hand, when the decision result is “unusable”,restoration of the region width may not be conducted. The region widthdecoder 218 is connected through a line L218 to the prediction signalgenerator 106, and the region width produced by the region width decoder218 is output through the line L218 to the prediction signal generator106.

The prediction signal generator 106, or prediction signal productionunit, has a similar function to the prediction signal generator of theencoding device 100 shown in FIG. 1. That is, the prediction signalgenerator 106 uses at least one of the prediction information associatedwith the target block and the prediction information associated with theneighbouring block (if necessary), and the region width received throughthe L218, so as to produce the prediction signal of the decoding targetblock from the reconstructed signal stored in the frame memory 108.Since detailed example operations of the prediction signal generator 106are described in FIG. 6, detailed description is omitted here. Theprediction signal generator 106 is connected through the line L106 tothe adder 210. The prediction signal generator 106 outputs the producedprediction signal through the line L106 to the adder 210.

The quantized transformed coefficient decoder 214 receives the encodeddata of the quantized transformed coefficients through the line L204 cfrom the data analyzer 204. The quantized transformed coefficientdecoder 214 entropy-decodes the received encoded data to restore thequantized transformed coefficients of the residual signal of the targetblock. The quantized transformed coefficient decoder 214 outputs therestored quantized transformed coefficients through a line L214 to theinverse quantizer 206.

The inverse quantizer 206 inversely quantizes the quantized transformedcoefficients received through the line L214 to restore the transformedcoefficients. The inverse transformer 208 receives the restoredtransformed coefficients through a line L206 from the inverse quantizer206 and applies an inverse discrete cosine transform to the transformedcoefficients to restore the residual signal (decoded residual signal) ofthe target block.

The adder 210, or adder unit, receives the decoded residual signalthrough a line L208 from the inverse transformer 208 and receives theprediction signal produced by the prediction signal generator 106through the line L106. The adder 210 produces a reconstructed signal ofthe target block by adding the received decoded residual signal to theprediction signal. The reconstructed signal is output through a lineL210 to the frame memory 108 and stored in the frame memory 108, orstorage unit. In other examples, the reconstructed signal may be storein any other storage unit internal to, or external to the imagepredictive decoding device 200. In addition, the reconstructed signal isalso output to the output terminal 212. The output terminal 212 outputsthe reconstructed signal to the outside, or external to the imagepredictive decoding device 200. (to a display, for example).

With reference to operations of the image predictive decoding device200, an image predictive decoding method according to one embodiment isdescribed below. FIG. 8 is a flowchart of the image predictive decodingmethod according to one example embodiment. As shown in FIG. 8, in thepresent image predictive decoding method, first in step S500, compresseddata is input through the input terminal 202. Then in step S502, atarget block that is the target of the process is selected.

Then in step S504, the data analyzer 204 analyzes the compressed dataand extracts encoded data of prediction information associated with thetarget block that is a decoding target; of a region width; and ofquantized transformed coefficients. The prediction information isdecoded by the prediction information decoder 216 in step S506.

Next, the process proceeds to step S508. FIG. 9 is a detailed flowchartof an example of step S508 in FIG. 8. As shown in FIG. 9, in the processof step S508, first in step S600, at least two pieces of predictioninformation associated with the target block and a neighbouring blockare input in the decision unit 130.

Next in step S202, the decision unit 130 decides usability of theprediction information associated with the neighbouring block andoutputs a decision result. The operations of the decision unit 130 instep S202 is similar to the operations described in FIG. 5, so detaileddescription is omitted here.

Then in step S602, it is decided whether the decision result of thedecision unit 130 indicates “usable” or not. When the decision result instep S602 is true (Yes), that is, when the prediction information of theneighbouring block is usable, the region width decoder 218 decodes theencoded data of the region width to restore the region width of apartition (R2) of the target block in step S604. On the other hand, whenthe decision in step S602 is false (No), the region width decoder 218sets the region width of the partition (R2) of the target block to 0 instep S606.

Referring to FIG. 8 again, after step S508 ends, the process proceeds tostep S510. In step S510, the prediction signal generator 106 produces aprediction signal of the decoding target block from the reconstructedsignal by using at least one of the two pieces of prediction informationassociated with the target block and the neighbouring block (predictioninformation associated with the neighbouring block is used only when itis necessary), and/or the region width. Here, step S510 is the same asstep S110 described in FIG. 6.

In the following step S512, the quantized transformed coefficientdecoder 214 restores quantized transformed coefficients from the encodeddata; the inverse quantizer 206 restores transformed coefficients fromthe quantized transformed coefficients; and the inverse transformer 208produces a decoded residual signal from the transformed coefficients.

Then in step S514, the adder 210 produces a reconstructed signal of thetarget block by adding the prediction signal of the target block to thedecoded residual signal. In step S516, the reconstructed signal isstored in the frame memory 108 as the reconstructed signal forreproducing the next target block.

Then in step S518, when it is decided that the process on all blocks isincomplete, that is when the next compressed data exists, an unprocessedblock is selected as the target block in step S502 and the stepsthereafter are repeated. On the other hand, when the process on allblocks is completed in step S518, the process ends.

The image predictive encoding device and method as well as the imagepredictive decoding device and method have been described above, but theimage predictor encoding/decoding system is not limited to theembodiments mentioned previously. For example, the neighbouring block inthe above embodiment is the neighbouring block on the left of the targetblock, but it may be the neighbouring block on top of the target block.In other examples, a first neighbouring block may be on a first side ofthe target block, and a second neighbouring block may be on a secondside of the target block, where the sides of the target blocks may be atop, bottom, side, a surface, a perimeter, border, or any other boundaryor periphery of the target region.

FIG. 10 is a diagram describing another example of the neighbouringblock. In the example shown in FIG. 10, the target block Bt and theneighbouring block B2 are a 8×8 pixel block, and similarly a top-leftpixel position (horizontal position, vertical position) is set to (0,0), while a bottom-right pixel position is set to (7, 7). The partitionR2 is a region surrounded by pixel positions (0, 0), (7, 0), (0, w-1)and (7, w-1) and the region where the prediction information of theneighbouring block B2 is likely to be used to produce the predictionsignal. The region width of the partition R2 is w.

When the prediction information associated with the neighbouring blockB2 shown in FIG. 10 is used to produce the prediction signal of thepartition R2, a range of x in step S404 of FIG. 6 is 0 to 7, while arange of y is w to 7. In addition, the range of x in step S406 of FIG. 6is 0 to 7, while the range of y is 0 to w-1.

In addition, the neighbouring block may be at least two neighbouringblocks one of which is on a first side of the target block, such as onthe left of the target block, and the other is on a second side of thetarget block, such as the top of the target block, and it is possible toselect either of the at least two neighbouring blocks with respect toeach target block. In such case, the prediction signal generator 106 hasa function of performing the prediction process described with referenceto FIG. 4 and FIG. 10, and the region width determiner 134 includes afunction of selecting one or more of the neighbouring blocks having theprediction information that is used to predict the partition of thetarget block, that is, either the neighbouring block on the left, on theright, on the bottom, on the top and/or on any other side of the targetblock. Alternatively or in addition, in other examples, a firstneighbouring block is positioned along a first side of the target blockand a second neighbouring block is positioned along a second side of thetarget block. In addition, the region width encoder 136 includes afunction of encoding identification information that identifies theneighbouring block having the prediction information to be used toproduce the prediction signal of the target region, from the at leasttwo pieces of prediction information associated with the at least twoneighbouring blocks, while the region width decoder 218 includes afunction of decoding the identification information.

Detailed description is given below for step S108 when using an exampleof at least two neighbouring blocks on the left and on the top. In otherexamples, at least a first neighbouring block may be positioned along afirst side of the target block and at least a second neighbouring blockmay be positioned along a second side of the target block. Theneighbouring blocks may be, for example, contiguous with the edges ofthe target block. FIG. 11 is a flowchart showing detailed procedures ofanother example of step S108 in FIG. 3. As shown in FIG. 11, in theprocess of step S108 of the present example, at least two pieces ofprediction information associated with neighbouring blocks on a firstside and/or a second side, such as on the top of and on the left of thetarget block are input in the decision unit 130 in step S700.

Next, the decision unit 130 decides, in accordance with the proceduresshown in step S202 of FIG. 5, whether the prediction informationassociated with the neighbouring block on the left of the target block,or positioned neighbouring a first side of the target block, can be usedto produce the prediction signal of the partition of the target block,and outputs a decision result. Then in step S704, when it is decidedthat the decision result of the decision unit 130 indicates “unusable”(in the case of No), that is, when the decision result shows that theprediction information associated with the neighbouring block on thefirst side, such as on the left will not be used to produce theprediction signal of the partition of the target block; the procedureproceeds to the following step S202. The decision unit 130 decides, inaccordance with the procedures shown in step S202 of FIG. 5, whether theprediction information associated with the neighbouring block on the topof the target block, or positioned neighbouring a second side of thetarget block, can be used to produce the prediction signal of thepartition of the target block and outputs a decision result.

Then, in step S706, when it is decided that the decision result of thedecision unit 130 indicates “unusable” (in the case of No), that is,when the decision result shows that the prediction informationassociated with the neighbouring block on the second side, such as thetop, will not be used to produce the prediction signal of the partitionof the target block; the process of step S108 ends.

On the other hand, in step S706, when it is decided that the decisionresult of the decision unit 130 indicates “usable” (in the case of Yes),the region width determiner 134 determines, in step S708, the regionwidth w of the partition R2 (refer to FIG. 10) of the target block,where the prediction signal is produced by using the predictioninformation of the neighbouring block on the second side, such as thetop. Then, in the following step S208, the region width w is encoded bythe region width encoder 136.

On the other hand, back in step S704, when it is decided that thedecision result of the decision unit 130 indicates “usable” (in the caseof Yes), the decision unit 130 decides in the following step S202, inaccordance with the procedures shown in step S202 of FIG. 4, whether theprediction information associated with the neighbouring block on thesecond side, such as the top of the target block can be used to producethe prediction signal of the partition of the target block and outputs adecision result.

Then in step S710, when it is decided that the decision result of thedecision unit 130 indicates “unusable” (in the case of No), the regionwidth determiner 134 determines, in the following step S712, the regionwidth w of the partition R2 (refer to FIG. 2) of the target block, wherethe prediction signal is produced by using the prediction information ofthe neighbouring block on a first side, such as on the left. Then, theregion width w is encoded by the region width encoder 136 in thefollowing step S208.

On the other hand, in step S710, when it is decided that the decisionresult of decision unit 130 indicates “usable” (in the case of Yes), theneighbouring block having the prediction information to be used toproduce the prediction signal is selected in the following step S714from the neighbouring block on the first side, such as the left and theneighbouring block on the second side, such as the top.

Specifically, in step S714, the region width determiner 134 selectswhich of the prediction information of the neighbouring block on thesecond side, such as the top and the prediction information of theneighbouring block on the first side, such as the left is to be used toproduce the prediction signal of the partition of the target block. Themethod for selection is not limited, but for example, the region widthdeterminer 134 sets the widths of the neighbouring block and of thepartition R2, as shown in FIG. 2 and FIG. 10; produces the predictionsignal of the target block by using the prediction information of theneighbouring block and the prediction information of the target block;and selects a group of the neighbouring block and the region width thatmakes prediction errors of the target block the smallest. Then in thefollowing step S716, the region width encoder 136 encodes identificationinformation identifying the neighbouring block having the selectedprediction information. Next, in step S718, when it is decided that theneighbouring block on the first side, such as the left is selected, theprocess proceeds to step S712. On the other hand, in step S718, when itis decided that the neighbouring block on the first side, such as theleft is not selected, that is, when it is decided that the neighbouringblock on the second side, such as the top is selected, the processproceeds to step S708.

FIG. 12 is a flowchart showing detailed procedures of another example instep S508 of FIG. 8, which shows procedures used in decodingcorresponding to encoding where the process of FIG. 11 is used. As shownin FIG. 12, in this example, first in step S800, the predictioninformation associated with the neighbouring block on the first side,such as on the left of the target block and the prediction informationassociated with the neighbouring block on the second side, such as thetop are input in the decision unit 130. In other examples, theneighbouring blocks may be aligned neighbouring an edge, a surface, aside or any other boundary or perimeter of the target block.

In the following two steps, the decision unit 130 decides, in accordancewith the procedures shown in step S202 of FIG. 4, usability of theprediction information associated with the neighbouring block on thefirst side, such as on the left and usability of the predictioninformation associated with the neighbouring block on the second side,such as the top, and outputs a decision result.

Next, in step S802, the region width decoder 218 decides, based on thedecision result of the decision unit 130, whether the predictioninformation associated with either one of the two or more neighbouringblocks is usable or not. When the prediction information associated withany of the neighbouring blocks is unusable, the region width decoder 218sets, in step S804, the region width of the partition R2 in the decodingtarget block to a predetermined value, such as zero, and ends theprocess.

On the other hand, in step S802, when it is decided that the predictioninformation associated with either one of the at least two neighbouringblocks is usable, the region width decoder 218 decides, based on thedecision result of the decision unit 130, in the following step S806,whether the prediction information associated with each of the two ormore neighbouring blocks are usable or not. When the predictioninformation of the two or more neighbouring blocks are usable, theregion width decoder 218 decodes, in the following step S808,identification information to identify at least one of the neighbouringblocks from the encoded data and proceeds to step S812.

On the other hand, in step S806, when it is decided that the predictioninformation associated with any of the two or more neighbouring blocksis usable, the region width decoder 218 selects, based on the decisionresult of the decision unit 130, in the following step S810, theprediction information associated with any of the two or moreneighbouring blocks determined to be useable and proceeds to step S812.In step S812, the region width decoder 218 decodes a value of the regionwidth.

The prediction signal may be produced by using at least the predictioninformation associated with the neighbouring block on the first side,such as on the left of the target block and the prediction informationassociated with the neighbouring block on the second side, such as onthe top. In that case, the region width encoder 136 has a function ofencoding both groups of the at least two pieces of predictioninformation associated with the at least two neighbouring blocks and atleast two region widths, while the region width decoder 218 has afunction of decoding groups of the two or more pieces of predictioninformation and the two or more region widths. In addition, in thatcase, as shown in FIG. 13, prediction signals of four partitions R1 toR4 in the target block Bt are produced individually. In other examples,any number of partitions may be used.

Accordingly, the prediction signal generator 106 produces the predictionsignal of the partition R2 by using the prediction informationassociated with the neighbouring block B1 on the first side, such as onthe left, and produces the prediction signal of the partition R3 byusing the prediction information associated with the neighbouring blockB2 on the second side, such as on the top. In addition, the predictionsignal generator 106 may have a function of producing the predictionsignal of the partition R4. The method for predicting the partition R4,which may be given as a rule in advance, is not limited in the imagepredictor encoding/decoding system. Examples of the method include amethod for averaging the prediction signal of the partition R4 that isproduced based on the prediction information associated with theneighbouring block on the first side, such as the left, and theprediction signal of the partition R4 that is produced based on theprediction information associated with the neighbouring block on thesecond side, such as the top, with respect to a pixel unit; and a methodfor producing the prediction signal of the partition R4 based on theprediction information associated with the neighbouring block on theside, such as the top-left. In addition, there may be adopted a methodin which selection is automatically made, by using surrounding alreadydecoded data including the prediction information associated with theneighbouring blocks on the first side, such as the left and on thesecond side, such as the top, from the prediction information thatbelong to the neighbouring blocks on the first side and on the secondside; or a method of transmitting selection information.

Furthermore, the following modifications can be made in the imagepredictor encoding/decoding system.

Block Shape

In the description above, the partition of the target block isillustrated as rectangular, but as shown in the partitions R1 and R2 ofthe target block Bt in FIG. 14A, or as shown in the partitions R1 and R2of the target block Bt in FIG. 14B, the partition in any shape may beused. In such case, shape information is transmitted in addition to aregion width.

Block Size

In the description above, the block size is a fixed size, but as shownin A-C of FIG. 15, the target block Bt and the neighbouring block B1 maydiffer in size. In such case, as shown in A-C of FIG. 15, various shapescan be used as the shape of the partitions R1 to R3 in the target blockBt. The partitions to be constituted may be determined according tocircumstances, or the information indicating the neighbouring block maybe selected from a plurality of candidates and may be explicitlyencoded. In addition or alternatively, a predetermined rule may beprovided in advance (for example, a unit for selecting the region widthis aligned with the smaller one in block size).

Region Width Encoder and Decoder

In the region width encoder, not a region width value itself, butinformation identifying the region width may be encoded. In addition, inthe region width decoder, not the region width value itself, but theinformation identifying the region width may be decoded from the encodeddata, and the region width value may be restored, based on theinformation identifying the region width. For example, the region widthencoder prepares a plurality of candidates for the region width valuesof the partition in the target block and may encode the identificationinformation of the selected candidate. The region width decoder mayrestore the region width value based on the decoded identificationinformation. The candidates for the region widths may be determined inadvance by the encoder and the decoder, or may be transmitted for eachsequence unit or for each frame unit. In addition, the region widthencoder may encode a differential value between the region width valueof the partition in the target block and the region width of theneighbouring block. In such case, the region width decoder can restorethe region width value of the partition in the target block by addingthe already decoded region width value of the neighbouring block to thedifferential value decoded from the encoded data. Alternatively, theregion width encoder may encode information indicating that the regionwidth of the partition in the target block is the same as, matches,and/or is substantially similar to, the region width of the neighbouringblock. When the information indicating that the region width of thepartition in the target block is similar to the region width of theneighbouring block, is decoded, the region width decoder can use theregion width of the neighbouring block as the region width of thepartition in the target block. In this case, information indicating thatthe region width of the partition in the target block is different fromthe region width of the neighbouring block, as well as, informationidentifying the region width value or the region width, may betransmitted. When the information indicating that the region width ofthe partition in the target block is different from the region width ofthe neighbouring block, is decoded, the region width decoder furtherdecodes the information identifying the region width value or the regionwidth from the encoded data and may restore the region width value,based on the information identifying the region width. In addition, theregion width encoder may encode one or more information items foridentifying the region width. That is, one or more information itemsthat are capable of uniquely identifying the region width (for example,one or more bits) may be encoded. In such case, the region width decoderdecodes one or more information items from the encoded data and canrestore the region width, in accordance with the one or more informationitems.

Transformer, Inverse-Transformer

A transform process of the residual signal may be performed in a fixedblock size. The target region may be further divided into a size thatmatches with the partition, and with respect to each region produced bythe further division, the transform process may be performed.

Decision Unit

The neighbouring block, of which prediction information associated withthe neighbouring block can be used, is not limited to the neighbouringblock on a first side, such as the top of the target block and theneighbouring block on a second side, such as on the left of the targetblock. For example, when the prediction information is encodedbeforehand by one block line, all blocks located adjacent to the targetblock, such as four blocks, can be the neighbouring block, and thepieces of prediction information associated therewith can be used toproduce the prediction signal of the target block.

In addition, when the pieces of prediction information of all blocks ina picture is encoded beforehand, the prediction signal of each targetblock can be freely constituted by using a total of a predeterminednumber of pieces of prediction information associated with neighbouringblocks surround the target block, such as five (or nine, when includingleft-top, left-bottom, right-top and right-bottom) pieces of predictioninformation associated with surrounding four blocks and the targetblock.

Furthermore, even if the partition is provided when the target block andthe neighbouring block have the same, matching, or substantially similarprediction information, the encoding and decoding processing may notfail, so that a prediction signal production process of the imagepredictor encoding/decoding system can be realized when a decision unitis omitted.

About Decision of Decision Unit

In the description above, according to the predetermined rule for thedecision unit 130 to decide usability of the prediction informationassociated with the neighbouring block, it is decided that theprediction information associated with the neighbouring block is not tobe used, when the prediction information associated with theneighbouring block coincides with the prediction information associatedwith the target block, or when it is decided that the predictioninformation of the neighbouring block is in a unusable state. In thelatter case, when the neighbouring block is predicted by intra-pictureprediction and the target block is predicted by inter-pictureprediction, and in the opposite case; it may be decided that theprediction information associated with the neighbouring block is not tobe used. In addition, when a difference between a motion vector of theneighbouring block and a motion vector of the target block exceeds athreshold value, it may be decided that the prediction informationassociated with the neighbouring block is not to be used. Furthermore,when the block sizes of the neighbouring block and the target block aredifferent from each other, it may be decided that the predictioninformation associated with the neighbouring block is not to be used. Inthe description above, the prediction information associated with theneighbouring block and the target block are compared, but based onwhether the prediction signals produced with the at least two pieces ofprediction information are matching or not, usability of the predictioninformation associated with the neighbouring block may be decided.

Prediction Information

In the description above, the inter-picture prediction (motion vectorand reference picture information) is described as a method forproducing the prediction signal, but the image predictorencoding/decoding system is not limited to such prediction method. Theprediction method including the intra-picture prediction, luminancecompensation, bidirectional prediction, or backward prediction, may beapplied to the prediction signal production process of the imagepredictor encoding/decoding system. In such case, mode information, aluminance compensation parameter and the like are included in theprediction information.

Color Signal

In the description above, a color format is not particularly mentioned,but as to a color signal or a color-difference signal, a productionprocess of the prediction signal may be performed separately from aluminance signal. In addition, the production process of the predictionsignal of the color signal or the color-difference signal may beperformed in conjunction with the process of the luminance signal. Inthe latter case, when a resolution of the color signal is lower than theluminance signal (for example, the resolution is half in a horizontaldirection and in a vertical direction), the region width in theluminance signal may be controlled (for example, to even values), or atransformation equation from the region width of the luminance signal tothe region width of the color signal may be determined.

Block Denoising Processing

It is not mentioned above, but, when a block denoising process isperformed with respect to a reconstructed image, a denoising process maybe performed with respect to a boundary part of the partition of thetarget region.

The image predictor encoding/decoding system may include an imagepredictive encoding program enabling a computer to operate as the imagepredictive encoding device 100, and an image predictive decoding programenabling a computer to operate as the image predictive decoding device200 are described below.

FIG. 16 is a diagram showing an example of at least part of imagepredictor encoding/decoding system that includes an image predictiveencoding program as well as a non-transitory recordable medium accordingto one embodiment. FIG. 17 shows an image predictive decoding program aswell as a recording medium according to one embodiment. FIG. 18 is adiagram showing an example hardware configuration of a computer forexecuting a program recorded in the recording medium. FIG. 19 is aperspective view of the example computer for executing the programstored in the record medium.

As shown in the example of FIG. 16, an image predictive encoding programP100 is provided by being stored in a non-transitory record medium 10,computer readable medium and/or memory. As shown in FIG. 17, an imagepredictive decoding program P200 is also provided by being stored in thenon-transitory recording medium 10, computer readable medium and/ormemory. Instructions in the form of computer software, firmware, data orany other form of computer code and/or computer program readable by acomputer within the image predictor encoding/decoding system may bestored in the non-transitory recording medium. Examples of the recordingmedium 10 include recording media, such as floppy disks, CD-ROMs, DVDs,and ROMs; and semiconductor memories.

As shown in FIG. 18, an example computer 30 is provided with a readingdevice 12 such as a floppy disk drive, a CD-ROM drive device, and a DVDdrive device; a working memory (RAM) 14 including a resident operatingsystem; a memory 16 that stores a program stored in the record medium10; a display device 18 such as a display; a mouse 20 and a keyboard 22both of which are input devices; a communication device 24 thattransmits and receives data and the like; and a CPU 26, or processor,that controls the execution of the program. In one example, uponinsertion of the recording medium 10 into the reading device 12, thecomputer 30 becomes accessible to the image predictive encoding programP100 at least partly stored in the record medium 10 from the readingdevice 12, and is enabled by the program P100 to operate as the imagepredictive encoding device 100. In addition, upon the insertion of therecording medium 10 into the reading device 12, the computer 30 becomesaccessible to the image predictive decoding program P200 at least partlystored in the recording medium 10 from the reading out device 12, and isenabled by the program P200 to operate as the image predictive decodingdevice 200.

As shown in FIG. 19, the image predictive encoding program P100 and theimage predictive decoding program P200 may be provided through a networkas a computer data signal 40 superimposed on a carrier wave. In suchcase, the computer 30 stores in the memory 16 at least part of the imagepredictive encoding program P100 or the image predictive decodingprogram P200 that is received by the communication device 24, and canexecute the program P100 or P200.

As shown in FIG. 16, the image predictive encoding program P100 mayinclude at least part of a block division module P104, a predictionsignal production module P106, a storage module P108, a subtractionmodule P110, a transformation module P112, a quantization module P114,an inverse quantization module P116, an inverse transformation moduleP118, an adding module P120, and a quantized transformed coefficientencoding module P122, a prediction information estimation module P126, aprediction information storage module P128, a decision module P130, aregion width determination module P134, a prediction informationencoding module P132, a region width determination module P134, and aregion width encoding module P136.

Functions realized by executing each module described above are thesame, or substantially similar, as the functions of the image predictiveencoding device 100 described above. That is, the functions of eachmodule of the image predictive encoding program P100 are the same, orsubstantially similar as the functions of the block division unit 104,the prediction signal generator 106, the frame memory 108, thesubtractor 110, the transformer 112, the quantizer 114, the inversequantizer 116, the inverse transformer 118, the adder 120, the quantizedtransformed coefficient encoder 122, the prediction informationestimator 126, the prediction information memory 128, the decision unit130, the prediction information encoder 132, the region width determiner134, and the region width encoder 136.

The image predictive decoding program P200 may include at least part ofa data analysis module P204, a quantized transformed coefficientdecoding module P214, a prediction information decoding module P216, aregion width decoding module P218, the prediction information storagemodule P128, the decision module P130, an inverse quantization moduleP206, an inverse transformation module P208, an adding module P210, theprediction signal production module P106, and the storage module P108.

Functions realized by executing each module described above are thesame, or substantially similar as those of each component of the imagepredictive decoding device 200. That is, the functions of each module ofthe image predictive decoding program P200 are the same, orsubstantially similar as the functions of the data analyzer 204, thequantized transformed coefficient decoder 214, the predictioninformation decoder 216, the region width decoder 218, the predictioninformation memory 128, the decision unit 130, the inverse quantizer206, the inverse transformer 208, the adder 210, the prediction signalgenerator 106, and the frame memory 108.

As described above, the image predictor encoding/decoding system hasbeen described in detail based on the example embodiments. The presentinvention, however, is not limited to the above-described exampleembodiments. Various modifications can be made without departing fromthe scope of the invention. It will be apparent to those of ordinaryskill in the art that many more examples and implementations arepossible within the scope of the invention. Accordingly, the inventionis not to be restricted except in light of the attached claims and theirequivalents.

What is claimed is:
 1. An image predictive decoding method comprising:data extraction step for extracting, from compressed data where an imageis divided into a plurality of regions and encoded, encoded data ofprediction information that is used to produce a prediction signal of atarget region, encoded data of a region width of a partition, andencoded data of a residual signal; regional information restoration stepfor restoring the region width of the partition by decoding the encodeddata of the region width of the partition; prediction signal productionstep for, when specifying that the target region is not divided,producing a prediction signal of the target region from a reconstructedsignal by using prediction information restored from the encoded data ofprediction information, or specifying a neighbouring region among aplurality of neighbouring region neighbouring to the target region basedon identification information decoded from encoded data of theidentification information included in the compressed data to produce aprediction signal of the target region, by using prediction informationincluding (i) mode information that specifies an inter-pictureprediction method, (ii) a reference picture number, and (iii) a motionvector, all of which are attached to the specified neighbouring region;residual signal restoration step for restoring a reproduction residualsignal of the target region from the encoded data of the residualsignal; signal production step for producing the reproduction signal ofthe target region based on the prediction signal of the target regionand the reproduction residual signal; and storage step for storing thereproduction signal of the target region as the reconstructed signal. 2.An image predictive encoding method comprising: region division step fordividing an input image into a plurality of regions; predictioninformation estimation step for producing a prediction signal of a pixelsignal of a target region among the plurality of regions from areconstructed signal and obtaining prediction information that is usedto produce the prediction signal, as prediction information associatedwith the target region; prediction information encoding step forencoding the prediction information associated with the target region;partition determination step for determining a region width of apartition in the target region and where the prediction informationassociated with the neighbouring region is used to produce theprediction signal; partition encoding step for encoding information forspecifying a region width of a partition; prediction signal productionstep for, when specifying that the target region is not divided,producing a prediction signal of the target region from a reconstructedsignal by using prediction information attached to the target region, orspecifying a neighbouring region among a plurality of neighbouringregion neighbouring to the target region based on identificationinformation to produce a prediction signal of the target region, byusing prediction information including (i) mode information thatspecifies an inter-picture prediction method, (ii) a reference picturenumber, and (iii) a motion vector, all of which are attached to thespecified neighbouring region; residual signal production step forproducing a residual signal between the prediction signal of the targetregion and the pixel signal of the target region; residual signalencoding step for encoding the residual signal; residual signalrestoration step for producing a reproduction residual signal bydecoding encoded data of the residual signal; adding step for producinga reproduction signal of the target region by adding the predictionsignal to the reproduction residual signal; and storage step for storingthe reproduction signal of the target region as the reconstructedsignal.
 3. An image predictive decoder comprising a processor programmedto: extract, from compressed data where an image is divided into aplurality of regions and encoded, encoded data of prediction informationthat is used to produce a prediction signal of a target region, encodeddata of a region width of a partition, and encoded data of a residualsignal; restore the region width of the partition by decoding theencoded data of the region width of the partition; specify that thetarget region is not divided, (a) produce a prediction signal of thetarget region from a reconstructed signal by using predictioninformation restored from the encoded data of prediction information, or(b) specify a neighbouring region among a plurality of neighbouringregion neighbouring to the target region based on identificationinformation decoded from encoded data of the identification informationincluded in the compressed data to produce a prediction signal of thetarget region, by using prediction information including (i) modeinformation that specifies an inter-picture prediction method, (ii) areference picture number, and (iii) a motion vector, all of which areattached to the specified neighbouring region; restore a reproductionresidual signal of the target region from the encoded data of theresidual signal; produce the reproduction signal of the target regionbased on the prediction signal of the target region and the reproductionresidual signal; and store the reproduction signal of the target regionas the reconstructed signal.
 4. An image predictive encoder comprising aprocessor programmed to: divide an input image into a plurality ofregions; produce a prediction signal of a pixel signal of a targetregion among the plurality of regions from a reconstructed signal andobtaining prediction information that is used to produce the predictionsignal, as prediction information associated with the target region;encode the prediction information associated with the target region;determine a region width of a partition in the target region and wherethe prediction information associated with the neighbouring region isused to produce the prediction signal; encode information for specifyinga region width of a partition; when specifying that the target region isnot divided, (a) produce a prediction signal of the target region from areconstructed signal by using prediction information attached to thetarget region, or (b) specify a neighbouring region among a plurality ofneighbouring region neighbouring to the target region based onidentification information to produce a prediction signal of the targetregion, by using prediction information including (i) mode informationthat specifies an inter-picture prediction method, (ii) a referencepicture number, and (iii) a motion vector, all of which are attached tothe specified neighbouring region; produce a residual signal between theprediction signal of the target region and the pixel signal of thetarget region; encode the residual signal; produce a reproductionresidual signal by decoding encoded data of the residual signal; producea reproduction signal of the target region by adding the predictionsignal to the reproduction residual signal; and store the reproductionsignal of the target region as the reconstructed signal.
 5. Anon-transitory recording medium storing a computer program executed byan image predictive decoder to implement: extracting, from compresseddata where an image is divided into a plurality of regions and encoded,encoded data of prediction information that is used to produce aprediction signal of a target region, encoded data of a region width ofa partition, and encoded data of a residual signal; restoring the regionwidth of the partition by decoding the encoded data of the region widthof the partition; when specifying that the target region is not divided,(a) producing a prediction signal of the target region from areconstructed signal by using prediction information restored from theencoded data of prediction information, or (b) specifying a neighbouringregion among a plurality of neighbouring region neighbouring to thetarget region based on identification information decoded from encodeddata of the identification information included in the compressed datato produce a prediction signal of the target region, by using predictioninformation including (i) mode information that specifies aninter-picture prediction method, (ii) a reference picture number, and(iii) a motion vector, all of which are attached to the specifiedneighbouring region; restoring a reproduction residual signal of thetarget region from the encoded data of the residual signal; producingthe reproduction signal of the target region based on the predictionsignal of the target region and the reproduction residual signal; andstoring the reproduction signal of the target region as thereconstructed signal.
 6. A non-transitory recording medium storing acomputer program executed by an image predictive encoder to implement:dividing an input image into a plurality of regions; producing aprediction signal of a pixel signal of a target region among theplurality of regions from a reconstructed signal and obtainingprediction information that is used to produce the prediction signal, asprediction information associated with the target region; encoding theprediction information associated with the target region; determining aregion width of a partition in the target region and where theprediction information associated with the neighbouring region is usedto produce the prediction signal; encoding information for specifying aregion width of a partition; when specifying that the target region isnot divided, (a) producing a prediction signal of the target region froma reconstructed signal by using prediction information attached to thetarget region, or (b) specifying a neighbouring region among a pluralityof neighbouring region neighbouring to the target region based onidentification information to produce a prediction signal of the targetregion, by using prediction information including (i) mode informationthat specifies an inter-picture prediction method, (ii) a referencepicture number, and (iii) a motion vector, all of which are attached tothe specified neighbouring region; producing a residual signal betweenthe prediction signal of the target region and the pixel signal of thetarget region; encoding the residual signal; producing a reproductionresidual signal by decoding encoded data of the residual signal;producing a reproduction signal of the target region by adding theprediction signal to the reproduction residual signal; and storing thereproduction signal of the target region as the reconstructed signal.